1. Field of the Invention
The present invention relates to a socket for a coaxial electrical plug-in connector comprising an inner contact opening, an inner contact element located therein, and an outer plug surrounding the inner contact opening and being of a circular-cylindrical construction, said outer plug having an outer contact element.
The invention furthermore relates to an electrical connector plug comprising a plug body which an electrically insulating carrier element for an inner contact pin is affixed to, and comprising an outer contact element spaced radially from the inner contact pin relative to the longitudinal axis of said plug.
2. Description of the Related Art
Coaxial plug-in connectors of this type are known under the designation “cinch plugs” or “RCA plugs”, serving for establishing a detachable cable connection between consumer electronics devices for the purpose of asymmetrically transmitting audio or video signals.
Conventional RCA plugs usually have an outer contact of a hollow cylindrical construction arranged coaxially towards the inner contact pin. This outer contact is usually comprised of a ring-shaped metal strip having slots extending in axial direction. By means of this slotted metal strip, the plug engages in an outer plug of a pertaining cinch or RCA socket, said plug also being of a circular-cylindrical shape. The spring-resilient properties of the slotted metal strip of the outer contact are utilized for such RCA plug-in connectors to establish a friction-locked connection of the plug with the socket.
Known from EP 1 049 206 A2 is a socket for a coaxial electrical plug-in connector comprised of an outer contact element being of a circular cylinder construction. Mounted at the inside of the outer contact element is a spring-resilient contact wire, the curve of which may be helical at the inside of the outer contact element. The contact wire determines the plug-in and pull-out force for the connection of said socket with an appropriate plug.
A mounting socket for a coaxial electrical plug-in connector is furthermore known from JP 08-306443 A. With this socket, the outer contact element is of a circular cylinder construction, with elevations being provided on the outside of the outer contact element, said elevations extending on the outside of the outer contact element in a circular ring shape or like a broken helical curve. These elevations are designed to improve the contact properties of the outer contact element of the socket with the relevant outer contact element of a pertaining plug.
Another socket for accommodating a coaxial plug is known from DE 199 08 469 A1. The plug to be entered into said socket has a circumferential groove, thus leading to a latching of the plug in the socket.
Furthermore known from DE 199 27 713 C1 is a multiple coupler for coaxially shrouded sockets, which is destined for applications in high-frequency technology. Provided for said coupler is a tensioning device which serves to apply the clamping forces between resilient contact elements of plugs and the corresponding outer contact elements of the sockets to be contacted to establish the contact.
It is known that plug-in connectors of the type described hereinabove have sub-optimal properties with regard to the quality of transmitting audio and video signals. The coaxial arrangement composed of an inner contact pin and an outer contact basically determines the impedance with conventional plug-in connectors. A major problem is to be faced because the impedance of the plug is by no means adapted to the wave resistance of the applied cable, thus causing reflections of the transmitted signal at the point of connection. This problem attains specific relevance, if digital audio or video signals are transmitted with a high data rate through the plug-in connector. Due to non-linear signal distortion, this may lead to bit faults and substantial data losses, thus drastically diminishing the quality of playback of audio and video signals transmitted through the plug-in connector. However, it is disadvantageous that linear distortion occurs already on transmission of analogous audio and video signals, which adversely affects the quality of playback. Furthermore it is known that induced eddy currents may form due to the flow of electric current through the inner contact pin in the circular-cylindrical metal strip of the outer contact, said eddy currents interfering with the signal in a hardly predictable manner and thus adversely affecting the transmission of signals.
Known from WO 00/70717 is an RCA plug, which allows for establishing a plugged connection with a conventional RCA socket, whereby the disadvantages outlined hereinabove are partly avoided.
Instead of the usually slotted metal strip, the prior art RCA plug has an axially directed, pin-shaped outer contact element which is fixed relative to the inner contact pin by means of a carrier element made of plastic material in a functional position required for establishing the electrical contact. To hold the plug at the pertaining socket, a collar section also made of plastic material is molded to the carrier element, said collar section latching at the circular-cylindrical outer contact of the socket. The pin-shaped outer contact is embedded in the plastic material of the collar section, so that the contact pin is pressed from outside against the outer contact of the socket when the plug is plugged into the socket. The pin-shaped outer contact with the prior art RCA plug in its contact area is of a cylindrical or even spherical or ellipsoidal construction.
Though the impedance behavior of the RCA plug known from the printed publication mentioned hereinabove is clearly different from the impedance behavior of conventional RCA plugs as described before, which is particularly attributable to the waiver for the hitherto usual metal strip as mass contact which is arranged coaxially towards the inner contact pin. However, when establishing an electrical plug-in connection with an RCA plug of this type, there is a problem in that those negative properties described before still exist on the part of the socket, which the plug is plugged into. The inner contact opening where the inner contact pin of the plug plugged into the socket is located in a conventional RCA socket is entirely surrounded by the metallic body of the outer plug of the socket, which forms the outer contact element. The circular cylindrical metal shell of the outer plug basically determines the quite substantial capacitance of the plug-in connector. Besides, the eddy currents described hereinabove can be induced in the metallic shell of the outer plug, which adversely affect the transmission of signals.
Now, against this background, it is the task of the present invention to furnish a coaxial plug-in connector which largely avoids the disadvantages and problems outlined hereinabove. By way of this invention, it is particularly intended to provide a socket for a coaxial electrical plug-in connector which shows an improved impedance behavior with regard to the transmission of signals between consumer electronics devices and in which the occurrence of eddy currents on the outer contact element is particularly avoided.